Combine or subtract signals with resistor networks.
Summing amplifier: V_o=-R_f(V₁/R₁+V₂/R₂+…) mixes signals, used in DACs and audio mixers. A difference amplifier gives V_o=(R₂/R₁)(V₂-V₁) rejecting common-mode noise; instrumentation amps add input buffers for high CMRR.
An instrumentation amplifier amplifies a strain-gauge bridge output.
Summing and difference amplifiers combine signals with resistors, which is the basis of audio mixers and sensor bridges.
Combine or subtract signals with resistor networks.
Summing and difference amplifiers combine signals with resistors, which is the basis of audio mixers and sensor bridges.
Use four matched resistors so the output equals the gain times the difference between the two input voltages.
Mismatch causes common-mode signals to leak into the output, which degrades the rejection of unwanted signals.
Typical applications include mixing two audio channels in a small mixer, subtracting a reference from a sensor signal in a controller and combining a control input and a feedback signal in a motor loop.
Study "Inverting and non-inverting amplifiers" first (topic 19 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
Weighted sum by resistor ratio. Match resistors for CMRR. Bridge sensor amplifiers.
An instrumentation amplifier amplifies a strain-gauge bridge output.
The next topic is "Integrator and differentiator", which builds directly on this one.
It is classed as Beginner in Electronics & Embedded (topic 20 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.
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